你调用的对象是空的。 C＃RADTreeView Telerik

Question

I am creating RadTreeView nodes dynamically and I have created it successfully.But When I try to Add a sub-category node to it,sub-category is added successfully but at the end when I am reloading tree I am getting this error:

Object reference not set to an instance of an object.

[NullReferenceException: Object reference not set to an instance of an object.]
   Telerik.Web.UI.RadComboBox.OnInit(EventArgs e) +40
   System.Web.UI.Control.InitRecursive(Control namingContainer) +134
   System.Web.UI.Control.AddedControl(Control control, Int32 index) +191
   System.Web.UI.ControlCollection.Add(Control child) +86
   Telerik.Web.UI.GridPagerItem.InitializePagerItem(GridColumn[] columns) +23849
   Telerik.Web.UI.GridPagerItem.SetupItem(Boolean dataBind, Object dataItem, GridColumn[] columns, ControlCollection rows) +170
   Telerik.Web.UI.GridTableView.CreateTopPagerItem(Boolean useDataSource, GridColumn[] copiedColumnSet, Boolean isPagingEnabled, GridTHead thead) +93
   Telerik.Web.UI.GridTableView.CreateControlHierarchy(Boolean useDataSource) +1156
   Telerik.Web.UI.GridTableView.CreateChildControls(IEnumerable dataSource, Boolean useDataSource) +679
   System.Web.UI.WebControls.CompositeDataBoundControl.CreateChildControls() +149
   System.Web.UI.Control.EnsureChildControls() +83
   Telerik.Web.UI.GridTableViewBase.get_Controls() +15
   Telerik.Web.UI.GridTableView.GetGridTable() +15
   Telerik.Web.UI.RadGrid.PrepareRowsVisibility(GridTableView view) +33
   Telerik.Web.UI.RadGrid.PrepareItems() +308
   Telerik.Web.UI.RadGrid.ControlPreRender() +64
   Telerik.Web.UI.RadCompositeDataBoundControl.OnPreRender(EventArgs e) +41
   System.Web.UI.Control.PreRenderRecursiveInternal() +83
   System.Web.UI.Control.PreRenderRecursiveInternal() +168
   System.Web.UI.Control.PreRenderRecursiveInternal() +168
   System.Web.UI.Control.PreRenderRecursiveInternal() +168
   System.Web.UI.Control.PreRenderRecursiveInternal() +168
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +974

Dont understand this I tried to debug my code using debug point but everthing is executed alright but at the end I am getting this error.

Answer 1

是的，在对我的代码进行了长时间的研究之后，我得到的答案是我的网格被引用为null。但是很遗憾，这是一个如此著名的论坛，但没人能理解堆栈跟踪。

Answer 2

I had this issue after a postback with a radgrid, the problem was the Datasourse was null. To fix it you only have to set DataSource = ""